diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/mesa/drivers/dri/i915/i915_fragprog.c | 87 |
1 files changed, 51 insertions, 36 deletions
diff --git a/src/mesa/drivers/dri/i915/i915_fragprog.c b/src/mesa/drivers/dri/i915/i915_fragprog.c index bafc8f02b8..0a643719f8 100644 --- a/src/mesa/drivers/dri/i915/i915_fragprog.c +++ b/src/mesa/drivers/dri/i915/i915_fragprog.c @@ -43,9 +43,13 @@ #include "i915_context.h" #include "i915_program.h" +static const GLfloat sin_quad_constants[4] = { + 4.0, + -4.0, + 2.0, + -1.0 +}; - -/* 1, -1/3!, 1/5!, -1/7! */ static const GLfloat sin_constants[4] = { 1.0, -1.0 / (3 * 2 * 1), 1.0 / (5 * 4 * 3 * 2 * 1), @@ -337,7 +341,7 @@ upload_program(struct i915_fragment_program *p) while (1) { GLuint src0, src1, src2, flags; - GLuint tmp = 0; + GLuint tmp = 0, consts = 0; switch (inst->Opcode) { case OPCODE_ABS: @@ -686,51 +690,62 @@ upload_program(struct i915_fragment_program *p) case OPCODE_SIN: src0 = src_vector(p, &inst->SrcReg[0], program); tmp = i915_get_utemp(p); + consts = i915_emit_const4fv(p, sin_quad_constants); + /* Reduce range from repeating about [-pi,pi] to [-1,1] */ i915_emit_arith(p, - A0_MUL, + A0_MAD, tmp, A0_DEST_CHANNEL_X, 0, - src0, i915_emit_const1f(p, 1.0 / (M_PI)), 0); + src0, + i915_emit_const1f(p, 1.0 / (2.0 * M_PI)), + i915_emit_const1f(p, .5)); - i915_emit_arith(p, A0_MOD, tmp, A0_DEST_CHANNEL_X, 0, tmp, 0, 0); + i915_emit_arith(p, A0_FRC, tmp, A0_DEST_CHANNEL_X, 0, tmp, 0, 0); - /* By choosing different taylor constants, could get rid of this mul: - */ - i915_emit_arith(p, - A0_MUL, - tmp, A0_DEST_CHANNEL_X, 0, - tmp, i915_emit_const1f(p, (M_PI)), 0); + i915_emit_arith(p, + A0_MAD, + tmp, A0_DEST_CHANNEL_X, 0, + tmp, + swizzle(consts, Z, ZERO, ZERO, ZERO), /* 2 */ + swizzle(consts, W, ZERO, ZERO, ZERO)); /* -1 */ - /* - * t0.xy = MUL x.xx11, x.x1111 ; x^2, x, 1, 1 - * t0 = MUL t0.xyxy t0.xx11 ; x^4, x^3, x^2, x - * t1 = MUL t0.xyyw t0.yz11 ; x^7 x^5 x^3 x - * result = DP4 t1.wzyx, sin_constants - */ - i915_emit_arith(p, - A0_MUL, - tmp, A0_DEST_CHANNEL_XY, 0, - swizzle(tmp, X, X, ONE, ONE), - swizzle(tmp, X, ONE, ONE, ONE), 0); + /* Compute sin using a quadratic. While it has increased total + * error over the range, it does give continuity that the 4-component + * Taylor series lacks when repeating the range due to its + * sin(PI) != 0 behavior. + * + * The idea was described at: + * http://www.devmaster.net/forums/showthread.php?t=5784 + * + * If we're concerned about the error of this approximation, we should + * probably incorporate a second pass to include a x**4 factor. + */ - i915_emit_arith(p, - A0_MUL, - tmp, A0_DEST_CHANNEL_ALL, 0, - swizzle(tmp, X, Y, X, Y), - swizzle(tmp, X, X, ONE, ONE), 0); + /* tmp.y = abs(tmp.x); {x, abs(x), 0, 0} */ + i915_emit_arith(p, + A0_MAX, + tmp, A0_DEST_CHANNEL_Y, 0, + swizzle(tmp, ZERO, X, ZERO, ZERO), + negate(swizzle(tmp, ZERO, X, ZERO, ZERO), 0, 1, 0, 0), + 0); - i915_emit_arith(p, - A0_MUL, - tmp, A0_DEST_CHANNEL_ALL, 0, - swizzle(tmp, X, Y, Y, W), - swizzle(tmp, X, Z, ONE, ONE), 0); + /* tmp.y = tmp.y * tmp.x; {x, x * abs(x), 0, 0} */ + i915_emit_arith(p, + A0_MUL, + tmp, A0_DEST_CHANNEL_Y, 0, + swizzle(tmp, ZERO, X, ZERO, ZERO), + tmp, + 0); + /* result = tmp.xy DP sin_quad_constants.xy */ i915_emit_arith(p, - A0_DP4, + A0_DP3, get_result_vector(p, inst), get_result_flags(inst), 0, - swizzle(tmp, W, Z, Y, X), - i915_emit_const4fv(p, sin_constants), 0); + tmp, + swizzle(i915_emit_const4fv(p, sin_quad_constants), + X, Y, ZERO, ZERO), + 0); break; case OPCODE_SLT: |